Gas turbine engines for aircraft achieve thrust by discharging hot gases through the exhaust nozzle. Efficient operation for multi-mission application dictates the use of variable area convergent/divergent nozzles.
Variable convergent/divergent configuration is achieved in axisymmetric nozzles by the use of a plurality of circumferentially arranged flaps. Overlapping seals are located between adjacent flaps.
The hinge arrangement must be provided between each convergent flap or seal and each divergent flap or seal. Variations may be made during operation, of the throat and terminal discharge openings.
Increased maneuverability of the aircraft can be accomplished by thrust vectoring. Here the discharge of gas is vectored from the axial direction to achieve a thrust component which is up, down or sideways. As shown in U.S. Pat. No. 5,082,182 (Bruchez et al, issued Jan. 21, 1992) the vectoring may be accomplished by only. The convergent flaps and seals remain symmetrical.
The hinges between the convergent and divergent flap must be capable of rotation around both the radial axis and lateral axis of the hinge. The divergent seal must also maintain a seal against both adjacent flaps at all times to prevent leakage of the hot gas stream and loss of thrust. Furthermore a seal must be resonably maintained at the hinge between the convergent and divergent seals.
A seal hinge for this purpose must allow rotation around two axes in order to permit the divergent seal to move with and seal against the divergent flaps during vectoring. The hinge must maintain a reasonable seal at all conditions to prevent leakage of the hot gas stream and loss of thrust. The hinge must also fit within the limited space between the adjacent flap hinges.